I am trying to implement try again/cancel dialog box in windows 8. The dialog box shows fine the first time, but on clicking try again and failing again, I get a access denied exception on calling ShowAsync. I don't know why, but its strange sometimes the code works fine and I don't get the exception when I put breakpoints. really clueless here
here is the code.
async void DismissedEventHandler(SplashScreen sender, object e)
{
dismissed = true;
loadFeeds();
}
private async void loadFeeds()
{
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
{
try
{
RSSDataSource rssDataSource = (RSSDataSource)App.Current.Resources["RSSDataSource"];
if (rssDataSource != null)
{
await rssDataSource.DownloadFeeds();
await rssDataSource.GetFeedsAsync();
}
AdDataSource ads = (AdDataSource)App.Current.Resources["AdDataSource"];
if (ads != null)
{
await ads.DownloadAds();
}
rootFrame.Navigate(typeof(HomePageView));
Window.Current.Content = rootFrame;
}
catch
{
ShowError();
}
});
}
async void ShowError()
{
// There was likely a problem initializing
MessageDialog msg = new MessageDialog(CONNECTION_ERROR_MESSAGE, CONNECTION_ERROR_TITLE);
// Add buttons and set their command handlers
msg.Commands.Add(new UICommand(COMMAND_LABEL_RETRY, new UICommandInvokedHandler(this.CommandInvokedHandler)));
msg.Commands.Add(new UICommand(COMMAND_LABEL_CLOSE, new UICommandInvokedHandler(this.CommandInvokedHandler)));
// Set the command to be invoked when a user presses 'ESC'
msg.CancelCommandIndex = 0;
await msg.ShowAsync();
}
/// <summary>
/// Callback function for the invocation of the dialog commands
/// </summary>
/// <param name="command">The command that was invoked</param>
private void CommandInvokedHandler(IUICommand command)
{
string buttonLabel = command.Label;
if (buttonLabel.Equals(COMMAND_LABEL_RETRY))
{
loadFeeds();
}
else
{
// Close app
Application.Current.Exit();
}
}
Okay I found a quick solution,
define a IAsyncOperation class varialble
IAsyncOperation<IUICommand> asyncCommand = null;
and set it to the ShowAsync method of MessageDialog
asyncCommand = msg.ShowAsync();
In the command handler for retry/try again check if asyncCommand is not null and cancel the last operation if necessary
if(asyncCommand != null)
{
asyncCommand.Cancel();
}
Please let me if there is a better approach to this.